1. Technical Field
Exemplary aspects of the present invention generally relate to a driving device and an image forming apparatus including the driving device, and more particularly to an image forming apparatus such as a copier, a facsimile machine, a printer, or a multi-functional system including a combination thereof.
2. Description of the Related Art
Known electrophotographic image forming apparatuses such as a printer and a copier form an electrostatic latent image on a surface of a rotating latent image bearing member (hereinafter referred to as photosensitive drum), and subsequently, the electrostatic latent image is developed with toner into a visible image, known as a toner image. The toner image thus obtained is primarily transferred onto an endless belt (hereinafter referred to as intermediate transfer belt). The toner image on the intermediate transfer belt is then secondarily transferred onto a recording medium. Lastly, the toner image on the recording medium is fixed under heat and pressure applied thereto.
In such image forming apparatuses, precise control of rotation speed of the photosensitive drum and the intermediate transfer belt is required. More specifically, the photosensitive drum and the intermediate transfer belt need to be rotated at a constant speed. If the speed of rotation of the photosensitive drum and the intermediate transfer belt fluctuates, imaging failure such as jitter and unevenness of image density occurs. Furthermore, if the rotation speed continues to fluctuate at a certain frequency, unevenness of image density appears periodically over the entire image as banding or stripes on an output image. The banding derived from such fluctuation of the rotation speed degrades imaging quality significantly.
In view of the above, various techniques have been proposed to accurately rotate the photosensitive drum and the intermediate transfer belt. For example, a gear assembly is employed to adjust the rotation speed of the target. However, known gear assemblies tend to be heavy and large, complicating efforts to make an image forming apparatus as a whole as compact as is usually desired.